JPS59203256A - Information recording medium - Google Patents

Abstract

PURPOSE:To prevent attracting of dust to the surface of a recording layer, degeneration of the recording layer, deformation of a substrate, and flaws on the substrate by joining a pair of disc-shaped transparent substrates, which have recording layers on one faces, into a sandwich with specific inside and outside spacers so that recording layers are inside. CONSTITUTION:A pair of disc-shaped substrates 12 consisting of an acrylic resin or the like are joined with recording layers 11 inside through an inside spacer 13 and an outside spacer 14 so that a hollow part 15 is formed between them. The inside spacer 13 and the outside spacer 14 have step parts 16, which are fitted to circumferential edge parts of substrates 12, in both end face parts, and both tip parts of step parts 16 form projecting parts 17 projecting over upper faces and lower faces of substrates 12. Since spacers 13 and 14 have projecting parts 17, the mechanical strength of substrates 12 is increased, and deformation of substrates 12, generation of flaws on substrates 12, attracting of dust to recording layers 11, degeneration of recording layers 11, etc. are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air sandwich type information recording medium with improved deformation resistance and distortion resistance.

Recently, beams with high energy density such as laser light are used. Information recording media called so-called optical discs have been developed and put into practical use.

This type of recording medium basically has a disc-shaped transparent substrate made of glass or plastic, and Bi and Ss.

The recording layer or light reflecting layer (hereinafter referred to as recording layer) is made of metal, semimetal, or semiconductor such as IrL or Tg in the form of a thin film by vapor deposition or the like.

This type of recording medium does not require darkroom operation, provides high-density, high-contrast recording, allows add-on information (additional recording), and scans recorded information with laser light. However, during handling or storage of the recording medium, the surface of the recording layer may be scratched or dust may adhere to it, or it may oxidize or deteriorate due to contact with air. This may cause troubles such as errors, and this will have an adverse effect on writing and reading.

As one means for eliminating such defects, an air sandwich type information recording medium has been proposed.

That is, as shown in a cross-sectional view in FIG. The hollow portion 5 is sealed between the image recording layers.
A recording medium having a structure has been proposed. Note that the center hole is a hole into which the rotating shaft of the turntable is inserted, and information is written and read using a laser beam while rotating the recording medium.

Such a configuration can eliminate the above-mentioned drawbacks regarding the recording layer, but since the spacer simply has a rectangular cross section, the workability during assembly is poor, and the information In order to write or read data, laser light must be irradiated from the substrate side, so the substrate cannot be made very thick, and spacers like the one described above alone cannot provide sufficient stable mechanical strength; Even structured substrates can be deformed, distorted, or exhibit circumferential waviness during operation, which can have a significant impact on the writing and reading of information.

In order to improve the workability when assembling using the above-mentioned spacers, it has been proposed to provide a stepped portion on the spacer (see Japanese Patent Application Laid-Open No. 172541/1983), but this method also reduces the It is not a measure to prevent deformation, etc., and in order to prevent the latter deformation of the board, it has been proposed to provide flat reinforcing metal rings on the upper and lower end surfaces of the outer peripheral edge of the board (Japanese Patent Laid-Open No. 57 (Refer to Publication No. 172542) However, it is troublesome to install the ring, and since the reinforcing ring is installed after assembling the sandwich structure using spacers, double work is required, which impairs work efficiency and increases cost. It will be connected.

SUMMARY OF THE INVENTION An object of the present invention is to provide an air sandwich type information recording medium that has a simple structure and eliminates the above-mentioned drawbacks.

That is, in the present invention, two disc-shaped transparent substrates having a recording layer on one side are joined with spacers interposed on the inside and outside so that a hollow part is formed between the image recording layers with the recording layer inside. In the sandwich type information recording medium,
At least one of the inner spacer and the outer spacer has a stepped portion on which the peripheral edge of the disk-shaped substrate fits on both end surfaces thereof, so that the upper and lower ends of the stepped portion protrude from the upper and lower surfaces of both substrates. This is an air sandwich type information recording medium characterized in that it is formed as follows.

The present invention will be explained in detail below.

As the substrate of the present invention, transparent plastics such as glass, acrylic resin (polymethyl methacrylate), polycarbonate, polyethylene terephthalate, and polyvinyl chloride are used, and acrylic resin is particularly preferred.

The thickness of the substrate is 0.3 m or more, especially 1. o~1.5t
Rrm or so is preferable.

The material used as the recording layer is not particularly specific, and may be any material used in the art, such as Tg.

Zn, In, Sn, Zr, AII, CtL,
Metals such as Ga, Bi, Ay.

Semi-metals such as 85, solid conductors such as Gg and Si, and alloys and combinations thereof are used. To provide a recording layer using these materials on the substrate, vapor deposition, sputtering,
Ion platen j etc. are used, and the thickness of the recording layer is 3
00A-'L500A is appropriate. Furthermore, a protective layer may be provided on the recording layer, if necessary.

FIG. 2 is a schematic cross-sectional view showing one embodiment of the present invention, in which the recording layer is placed inside and bonded via an inner spacer 13 and an outer spacer 14 to form a hollow portion 15 between them. The inner spacer 13 and the outer spacer 14 have stepped portions 16, 16 on both end surfaces thereof, which fit into the peripheral edge of the substrate, and the tips of the stepped portions 16° and 160 are located on the upper surface of the substrate 12 and 12. A protrusion 17.degree. 17 with a height of about 1 to 3 degrees is formed extending beyond the lower surface.

According to the present invention, since the spacer having the above shape is used, the board can be assembled easily, and the raised part forms a ring-shaped reinforcing part at the peripheral edge of the board, so that The mechanical strength of the substrate can be improved and deformation, distortion, etc. of the substrate can be prevented. Furthermore, circumferential undulations during operation can be reduced. Furthermore, the presence of the protruding portion of the spacer can prevent the substrate surface from being scratched even if the recording medium is placed directly on a table or the like.

Although it is preferable that the protrusion be provided on both the inner and outer spacers as in the above embodiment, the protrusion may be provided on only one of the spacers.

Note that the spacer may be made of the same plastic as the substrate, but it is preferable to use metal such as aluminum or aluminum alloy.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional air sand inch information recording medium, and FIG. 2 is a sectional view showing an embodiment of the air sand inch information recording medium of the present invention. 1.11... Recording layer 2.12... Substrate 6.
4.13. i4...Spacer 5, 15...Hollow part 16...Step part 17...Protrusion part Agent Patent attorney (8107) Kiyotaka Sasaki (and 3 others) Figure III

Claims (1)

[Claims] Two disc-shaped transparent substrates each having a recording layer on at least one of the substrates are joined with a strip interposed between the inside and outside so that the recording layer is placed inside and a hollow portion is formed between the image recording layers. In the air sandwich type information recording medium, a step portion into which a peripheral edge portion of the disk-shaped substrate fits is provided on both end surfaces of at least one of the inner spacer and the outer spacer. An air sandwich type information recording medium characterized in that the upper and lower ends of the inner substrate are formed so as to protrude from the upper and lower surfaces of the inner substrate.